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E Jang

Publications and source records attributed to E Jang.

4 recordsLinked to original sources
PubMed1993

Nitric oxide synthase in the autonomic nervous system of canine ileum.

The synaptosomes from canine ileal deep muscular plexus possess a nitric oxide (NO)-sensitive soluble guanylate cyclase, as demonstrated by approximately 3- to 4-fold elevation of synaptosomal cyclic GMP levels in the presence of either 1 mM sodium nitroprusside or L-arginine (20-1,000 microM) plus 1 mM NADPH. The activating effect of L-arginine on synaptosomal soluble guanylate cyclase was related to its enzymatic conversion to citrulline by NO synthase. The synaptosomal NO synthase was found to exhibit both calcium-independent and calcium/calmodulin-dependent components accounting for approximately 2- to 2.5-fold and 7- to 8-fold increases in the basal activity, respectively. The absolute magnitude of these activities was several-fold greater compared to the activities observed in the isolated cells of circular smooth muscle. The synaptosomal Ca-independent and Ca/calmodulin-dependent NO synthase activities were inhibited by methylene blue and L-NG-arginine methyl ester. The NO synthase activity was also attenuated in the presence of cyclic AMP (10 microM). Such an inhibition was related primarily to the suppression of Ca-independent activity. The ability of enteric nerves to generate NO from L-arginine strongly suggests the involvement of this process in the biochemical mechanisms underlying the neurogenic control of intestinal motility.

Amino Acid Oxidoreductases↗
PubMed1991

Alpha 2-adrenergic receptors on the circular smooth muscle of canine small intestine.

We have studied the distribution and properties of alpha 2-adrenergic receptors in the circular muscle layer (containing deep muscular plexus) of canine small intestine. Using radioactivity labelled rauwolscine, we located the binding sites to the neuronal membranes supporting the prejunctional action of alpha 2-adrenergic agents in the gut. Moreover, although the functional data to suggest the existence of postjunctional alpha 2-adrenergic receptors coupled to contraction are not available so far, we measured a substantial number of rauwolscine binding sites on the smooth muscle plasma membranes. Scatchard and Hill analyses of the saturation data were indicative of the presence of a single high affinity site (Hill coefficient 0.996) with a KD value of 8.8 nM and the maximum number of binding sites (Bmax) of 313 fmol/mg of protein. Competition studies suggested the presence of multiple subtypes of alpha 2-adrenoceptors.

Animals↗
PubMed1989

Calcium channel binding in nerves and muscle of canine small intestine.

Using [3H]-nitrendipine (Nit) and [125I]-omega conotoxin (w-CTX), the cellular and subcellular distribution of calcium channel subtypes in the homogenates of canine small intestinal circular muscle was studied. Nit. bound to the membranes from the circular smooth muscle cells (PM) and to the synaptosomal membranes from the deep muscular plexus (DMP); the Kd and Bmax values of Nit binding from these two sources were similar (Kd 0.4 +/- 0.16 nM and 0.77 +/- 0.24 nM; Bmax 206 +/- 22 and 192 +/- 39 fmol/mg of protein in DMP and PM respectively). w-CTX, however, bound only to the DMP (Kd 18.41 +/- 7.5 pM, Bmax 265 +/- 36 fmol/mg of protein). In DMP, nifedipine (10(-6) M) failed to interact with the binding of w-CTX; similarly, no modulation of Nit binding with unlabelled w-CTX (10(-7) M) could be detected. Therefore w-CTX and Nit binding sites represent two distinct, non-interactive and differentially distributed binding sites in canine small intestine.

Animals↗